Emergency shutdown mechanism for centrifugal compressor

ABSTRACT

A switch is mounted on a bracket fixed in the compressor casing and has contacts connected in a control circuit means for the impeller driver. Upon actuation, the contacts of the switch are cooperable with the circuit means to deenergize the driver. A lever is pivotally mounted on the bracket and in normal position restrains actuation of the switch contacts. Upon the impeller driving shaft shifting from normal operating position, a projection on the shaft moves the lever from normal position permitting actuation of the switch contacts to effect stoppage of the impeller driver.

United States Patent Anderson et al.

[54] EMERGENCY SHUTDOWN MECHANISM FOR CENTRIFUGAL COMPRESSOR [72]inventors: Carl M. Anderson; James W. En-

dress, both of Syracuse, NY.

[73] Assignee: Carrier Corporation, Syracuse, N.Y.

[22] Filed: July 8, 1971 [21] Appl. No.: 160,691

[52 us. Cl ..417/33, 192/129 A, ZOO/61.45, 417/44 51 Int. Cl ..F04b49/02 [58] Field of Search ..417/1, 33, 44; 308/15; 184/64; 200/6145 R;192/129 A [56] References Cited UNITED STATES PATENTS Schenck ..192/ 129A 1 Oct. 24, 1972 Blum ..200/61.45 R Conrath ..200/61.45 R

Primary Examiner-Carlton R. Croyle Assistant Examiner-R. J. SherAttorney-Harry G. Martin, Jr. et al.

[57] ABSTRACT A switch is mounted on a bracket fixed in the compressorcasing and has contacts connected in a control circuit means for theimpeller driver. Upon actuation, the contacts of the switch arecooperable with the circuit means to deenergize the driver. A lever ispivotally mounted on the bracket and in normal position restrainsactuation of the switch contacts. Upon the impeller driving shaftshifting from normal operating position, a projection on the shaft movesthe lever from normal position permitting actuation of the switchcontacts to effect stoppage of the impeller driver.

4 Claims, 4 Drawing Figures P'ATENTEDHBI 24 I972 SHEET 1 BF 2 L': c \i IFIG. I

INVENTOR. CARL MANDERSON ATTORNEY PATENTED 24 I97? 3,700,355

sum 2 or 2 CARL M. ANDERSON BY JAMES DRESS ATTORNEY EMERGENCY SIIU'IDOWNMECHANISM FOR CENTRIFUGAL COMPRESSOR BACKGROUND OF THE INVENTION Variousforms of automatic shutdown mechanisms have been proposed to stopcentrifugal gas compressors in the event the shaft carrying the impellershifts from normal operating position. Certain of said mechanismsfunction satisfactorily. However, they are expensive to manufacture andassemble into the compressor structures. This invention has as an objectan automatic emergency shutdown mechanism for a centrifugal gascompressor embodying a structural arrangement, particularly economicalto manufacture and assemble into the compressor structure and which isrugged and durable in use.

SUMMARY OF THE INVENTION A commercially available switch having a springactuated plunger for automatically actuating the contacts, such as aMicroswitch, is fixed on a bracket in the compressor casing. A lever'pivotally mounted on the bracket is arranged with one end portion forengagement by a projection on the impeller shaft as it shifts fromnormal operating position. Upon such engagement, the lever is swung outof contact with the actuating plunger of the switch, deenergizing theimpeller driver through a control circuit means in which the contacts ofthe switch are connected. Upon movement of the lever by the shaft, theswitch contact plunger maintains the end of the lever spaced from thepath of movement of the projection on the shaft.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a lengthwise sectional viewof a centrifugal compressor embodying our invention with a portion ofthe casing shown in elevation and including a schematic representationof the driver.

FIG. 2 is an enlarged view of the safety shutdown mechanism as shown inFIG. 1.

FIG. 3 is a view taken on line 3-3, FIG. 2, and

FIG. 4 is a view taken on line 4-4, FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The impellers 10, 11 are mountedon an impeller drive shaft 12. The shaft 12 is journaled in bearingsmounted in a casing having upper and lower sections l3, l4 detachablysecured together as by bolts 15, see FIG. 1. A driver 17 as an electricmotor, steam turbine or the like is operatively connected to theimpeller shaft 12 to efl'ect rotation thereof.

Control circuitry is provided for the driver 17 and includes a controlelement 20 connected by line 21 to the contacts of a switch 23. When thecontacts of the switch 23 are actuated, the control element functions todeenergize the driver 17.

A lug 26 is formed on the inner surface of the top casing section 13. Abracket 27 is mounted on the lug 26 as by bolts 29. The bracket 27 is ofright angle form in cross section having side flanges 30, 31. The flange31 is formed with elongated apertures 35 through which the mountingbolts 29 extend. With this arrangement, the bracket 27 may be adjustedtoward and from the impeller drive shaft 12.

The switch 23 is fixed to the flange 31 of the bracket, as by screws 40,and is constructed with a contact actuating plunger 43 extending throughan aperture 44 in the flange 30 of the bracket 27. u

A lever 45 is pivotally mounted intermediate its ends to the flange 30by bolt 47. As the lever 45 is moved about its pivot 47, one end of thedriver is moved in to and out of engagement with the plunger 43. Thesurface of the lever contacting the plunger 43 is formed with adepression 50. The plunger 43 is spring pressed outwardly and when theouter end of the plunger is seated in the recess 50, the lever 45 isyieldingly restrained against movement about the pivot 47 In thisposition, shown in full line in FIG. 2 and in dotted line in FIG. 3, theopposite end of the lever is located in proximity to the impeller shaft12.

The impeller shaft 12 is provided with a projection 51 located to engagethe free end of the lever 45 upon the impeller shaft shifting axially orradially from normal operating position. Upon the projection 51 engagingthe lever 45, it is moved from the dotted line position in FIG. 3 to thefull line position. Accordingly, the opposite end of the lever 45 ismoved out of engagement with the plunger 43. The movement of the springpress plunger is such that a substantial end portion of the plungerextends outwardly from the flange 30 of the bracket, as shown in FIG. 4,and serves to prevent return movement of the lever 45. That is, when thelever 45 has been tripped, it is held in trip position shown in fullline, FIG. 3, with the free end of the lever spaced from the path inwhich the projection 51 moves, the path being indicated by the line 53.This is advantageous in that it prevents the projection 51 from engagingwith the free end of the lever during reverse rotation of thecompressor. During the coast down period of the centrifugal compressor,there is a time when the high pressure gas will backflow through themachine .and effect reverse rotation of the impellers and the shaft 12.

The shutdown mechanism described embodies a low cost structure which isconveniently mounted in the compressor casing, and which functions todeenergize the compressor driver prior to the movement of the impellersand impeller drive shaft from normal operating position, prior to theengagement of the rotating parts with the frame structure or casing ofthe machine.

We claim:

1. A centrifugal refrigeration compressor including a casing, animpellerdrive shaft joumaled in said casing, a driver operatively connected tosaid shaft for effecting rotation thereof, said shaft having a radiallyextending projection, a safety shutdown mechanism for deenergizing saiddriver upon said impeller shaft shifting from normal operating position,said mechanism comprising a control circuit means for said driver, abracket fixedly mounted in said casing, a switch mounted on said bracketand having contacts connected in said control circuit and operable whenactuated to cause deenergization of said driver, said contacts beingmounted in an enclosure, an axially movable contact actuating plunger,means yieldingly urging said plunger outwardly out of said enclosure foractuation of said contacts, a lever pivotally mounted on said bracketfor movement in to and out of engagement with said plunger, said levernormally engaging said in claim 1, wherein upon movement of said leverout of engagement with said plunger for outward movement thereof, saidplunger is effective to maintain said lever out of normal position.

4. A centrifugal refrigeration compressor as set forth in claim 1,wherein the axis of the pivotal mount for said lever is located inspaced parallel relation to the axis of said plunger and said impellerdrive shaft.

1. A centrifugal refrigeration compressor including a casing, animpeller drive shaft journaled in said casing, a driver operativelyconnected to said shaft for effecting rotation thereof, said shafthaving a radially extending projection, a safety shutdown mechanism fordeenergizing said driver upon said impeller shaft shifting from normaloperating position, said mechanism comprising a control circuit meansfor said driver, a bracket fixedly mounted in said casing, a switchmounted on said bracket and having contacts connected in said controlcircuit and operable when actuated to cause deenergization of saiddriver, said contacts being mounted in an enclosure, an axially movablecontact actuating plunger, means yieldingly urging said plungeroutwardly out of said enclosure for actuation of said contacts, a leverpivotally mounted on said bracket for movement in to and out ofengagement with said plunger, said lever normally engaging said plungerand restraining outward movement thereof, said lever having an endportion terminating in close adjacency to the path of revolution of saidprojection, said lever being movable about said pivotal mounting out ofengagement with said plunger upon contact by said projection.
 2. Acentrifugal refrigeration compressor as set forth in claim 1, whereinsaid lever is formed with a depression for the reception of the outerend of said plunger.
 3. A centrifugal refrigeration compressor as setforth in claim 1, wherein upon movement of said lEver out of engagementwith said plunger for outward movement thereof, said plunger iseffective to maintain said lever out of normal position.
 4. Acentrifugal refrigeration compressor as set forth in claim 1, whereinthe axis of the pivotal mount for said lever is located in spacedparallel relation to the axis of said plunger and said impeller driveshaft.